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Strain resulting from the collision of India with Asia has caused fundamental changes to Asian drainage patterns, but the timing and nature of these changes are poorly understood. One frequently proposed hypothesis involves the connection of the palaeo Tsangpo drainage to a precursor to the Irrawaddy River of central Myanmar in the Palaeogene. To test this hypothesis, we studied the provenance of Palaeogene fluvio-clastic sedimentary rocks that crop out in central Myanmar, namely the Late Middle Eocene-Early Oligocene Pondaung and Yaw Formations. Isotopic analysis on bulk-rock and petrographic data indicate a primary magmatic arc source, and a secondary source composed of recycled, metamorphosed basement material. Although the exact location of both sources is hardly distinguishable because Burmese and Tibetan provinces share common lithological features, the presence of low-grade metamorphic fragments, the heterogeneity in Sr-Nd isotopic values of bulk sediments and westward-directed palaeoflow orientations indicate a proximal source area located on the eastern Asian margin. Central Myanmar was the locus of westward-prograding deltas opening into the Indian Ocean, supplied by the unroofing of an Andean-type cordillera that extended along the Burmese margin. We found no evidence to support a palaeo Tsangpo-Irrawaddy River, at least during the Late Eocene.

Turbidity currents commonly bypass sediment in submarine channels on the continental slope, and deposit sediment lobes farther down-dip on the flat and unconfined abyssal plain. Seafloor and outcrop data have shown that the transition from bypass to deposition usually occurs over complex zones referred to as channel–lobe transition zones (CLTZs). Recognition of these zones in cores and outcrop remains challenging due to a lack of characteristic sedimentary facies and structures. This paper focuses on Unit E of the Permian Fort Brown Formation in the Karoo Basin, South Africa, in the Slagtersfontein outcrop complex, which has previously been interpreted as a CLTZ. This study integrates thin-section micrographs, sedimentary facies, bed-set and stratigraphic architecture, and palaeoflow directions to achieve a multiscale analysis of CLTZ features. A novel process-based facies scheme is developed to evaluate deposits in terms of the depositional or erosional tendencies of the flows that formed them. This scheme allows bypass to be distinguished from depositional zones by the spatial distribution of certain sediment facies. Areas of net sediment bypass were predominantly marked by erosive sediment facies and a larger variability in palaeoflow direction while depositional areas showed a lower variability in palaeoflow directions. Metre-scale structures in the bypass-dominated area reveal seafloor erosion and scour formation. Field relations suggest the presence of a ∼500 m long mega-scour in the CLTZ. The characteristic structures documented here are applicable for identifying CLTZs in sparse datasets such as outcrops with limited palaeogeographical context and sediment cores obtained from subsurface systems.

In the Central Iberian Zone, the Cadomian orogenic collapse is represented by chaotic megabreccias, olistostromes and mélange deposits reflecting a drastic change from slope-related deposits, fed by denudation of the Cadomian arc, to offshore-dominant settings episodically punctuated by phosphogenetic processes. In the Ibor and Alcudia anticlines, the pre-rift unconformity is marked by paraconformable to angular discordant contacts separating variable tilted strata of the Ediacaran Lower Alcudian – Domo Extremeño Supergroup and the upper Ediacaran – lower Terreneuvian Ibor Group from the overlying Terreneuvian San Lorenzo and Fuentepizarra formations. The sedimentation of the San Lorenzo Formation reflects two palaeogeographic scenarios: (i) a low-angle stable basement recording shoaling-upward siliciclastic cycles, and (ii) perturbations of basement fault scarps feeding slope-related conglomeratic channels, with NE-directed palaeocurrents, and sourced from topographic palaeohighs controlled by the movement along synsedimentary normal fault systems, such as the so-called El Guijo Fault. The intra-Fortunian age of the pre-rift unconformity is constrained by the ichno- and microfossil content of the succession, and is bracketed between the first occurrence of Treptichnus pedum in the Arrocampo Formation (Ibor Group) and of Anabarella plana in the Fuentepizarra Formation.

Determining the provenance of sedimentary basin fill in the northern Qaidam Basin is a key step toward understanding the sedimentary system dynamics and mountain-building processes of the surrounding orogenic belts in Tibet. The exceptionally thick (average of 6-8 km) Cenozoic fluvio-lacustrine deposits in the northern Qaidam Basin were once thought to have been eroded from the nearby northern Qaidam Basin margin and the southern Qilian Shan and to reflect the prolonged thrust-related exhumation of these orogenic belts. However, several recent studies, based mainly on paleocurrent and detrital zircon U-Pb age data, suggested that they were derived from the distant East Kunlun Shan to the south, or the Qimen Tagh to the southwest (at least 200 and 350 km from the northern Qaidam Basin, respectively). That model assumed that the East Kunlun Shan and Qimen Tagh formed significant topographic barriers during the earliest sedimentation of Cenozoic strata (e.g., the Lulehe Formation) in the northern Qaidam Basin. Therefore, the tectonic significance of the provenance of the Lulehe Formation remains a fundamental problem in understanding the postcollisional uplift history of the northern Tibetan Plateau. To address this issue, we conducted sedimentological and paleocurrent analyses of the Lulehe Formation and detrital zircon U-Pb dating of Mesozoic strata in the northern Qaidam Basin. The results, in combination with existing paleocurrent and seismic reflection data, collectively indicate that although the source area cannot be specified by matching zircon U-Pb ages in sedimentary rocks with crystalline basement source rocks, other evidence points consistently to a unified proximal northerly source area (the northern Qaidam Basin margin and the southern Qilian Shan). Our results emphasize that noncrystalline basement rocks (e.g., Mesozoic sedimentary rocks) in fold-and-thrust belts should be taken into consideration when seeking potential source areas by correlating zircon U-Pb ages of siliciclastic detritus with related basement rocks. In addition, this study strongly supports the claim that variations in the proportions of age populations should be used with caution when determining source terrane by comparisons of age distributions.

Based on the results of the expedition works during the 55th and 57th cruises of the R/V Akademik Nikolai Strakhov in the area of the King’s Trough mesostructural complex (the eastern flank of the MAR), seismoacoustic profiling data of the upper part of the sedimentary cover are obtained. Reference reflectors, which were correlated with the DSDP 608 and IODP U1312 deep-sea drilling holes, are identified from the seismoacoustic sections. The sections cover the entire Quaternary sediment record (glacial cycles) and a part of the Upper Pliocene sediment record. Sedimentation rates within the different structures of the King’s Trough are calculated as a result of the works. During the past 1.5 Ma, sedimentation rates have been slightly different across the study area from background sedimentation rates, while earlier sedimentation rates were recorded to exceed the background ones by several times. There is a period of sharply increased sedimentation rates (up to 180 m/My) at ca. 1.5 Ma, which may be due to abrupt climate changes and ocean level fluctuations. Prior to the onset of the Mid-Pleistocene Transition ~1.5 Ma ago, a bottom current might have flowed along the bottom of the western part of the King’s Trough, which caused high sedimentation rates in the bottom of the trough. The current stopped after the onset of the transition, which could be due to regional restructuring of the Atlantic Meridional Overturning Circulation. These conclusions are correlated with sedimentation rates and changes in ocean surface temperature based on the data from IODP U1313.

Lithofacies and biostratigraphical analysis has enabled the establishment of a stratigraphic event framework for Ludfordian and Pridoli strata in south Wales and the Welsh Borderland. In SW Wales, the Golden Grove Axis acted as a structural hinge separating the shallow marine storm-influenced Cae’r mynach Seaway from a pediment surface above which Ludfordian colluvium (Abercyfor Formation) was deposited. The Axis seeded four NW-derived river-influenced delta progrades of Leintwardinian to early Pridoli age (Tilestones Formation). A NE-sourced early Pridoli wave-influenced delta deposited the Downton Castle Sandstone Formation (DCSF), coeval to the youngest Tilestones prograde, with a lateral interface existing between Mynydd Epynt and the Clun Forest area. Except for the Malverns area, the DCSF is no longer recognized south of the Neath Disturbance. Early Pridoli forced regression promoted widespread subaerial exposure north of the Neath Disturbance, with incision into tracts close to the Welsh Borderland Fault System. The basinward-shift in facies belts resulted in marine erosion and deposition of a phosphatic ravinement pebble lag. The wave-influenced Clifford’s Mesne Sandstone Formation delta subsequently seeded on the Gorsley Axis with tidally influenced Rushall Formation accumulating in a back-barrier setting. The Pwll-Mawr Formation records the easterly advance of coeval coastal deposits on the western side of the remnant Cae’r mynach Seaway. Behind migrating delta coastlines, green muds accumulated on coastal plains (Temeside Mudstone Formation) with better drained red dryland alluvium (Moor Cliffs Formation) charting expansion of Old Red Sandstone lithofacies. Mid-Pridoli incision preserves the Pont ar Llechau Formation estuarine valley fill.

The intracontinental Ordos Basin hosts many large uranium deposits, and its evolution was controlled by the surrounding orogenic belts during the Paleozoic to Mesozoic. Paleocurrent data of the Jurassic Zhiluo Formation reveal that its sedimentary detritus were transported dominantly from southwest to northeast in the basin. However, the detrital zircon age pattern of the Zhiluo Formation is similar to those of the Inner Mongolia Paleo-uplift, the Central Asian Orogenic Belt (CAOB), the Yinshan Block, and the Khondalite Belt to the north but is remarkably different from those of the Qinling Orogenic Belt (QOB) and the North Qilian Belt to the south. Discriminant diagrams using immobile elements also reveal that the detritus of the Zhiluo Formation are dominated by felsic volcanic rocks and andesitic arc rocks, consistent with rock types in its northern orogenic units. The Zhiluo sandstones show high chemical index of weathering values (68–83), suggesting long-distance transportation and intensive weathering. These lines of evidence demonstrate that rocks from the Zhiluo Formation were recycled from underlying Permian-Triassic sediments that were ultimately sourced from the northern orogenic units. The Ordos Basin has a three-stage growth that was controlled by the formation and tectonic evolution of the QOB to the south and the CAOB to the north during the Late Carboniferous to Jurassic.

We determined the provenance, tectonic setting, and weathering characteristics of weakly metamorphosed Mesoarchean siliciclastic rocks from the Singhbhum craton, eastern India, on the basis of their petrographic and geochemical compositions. The 1.5-km-thick siliciclastic succession, formally introduced here as the Keonjhar Quartzite, unconformably overlies the Singhbhum Granite (3.1-3.4 Ga) and has been assigned a Mesoarchean depositional age on the basis of a youngest detrital zircon of 3.01 Ga and intrusive granitoids with ages of not less than 2.8 Ga. Their highly matured and recycled nature is reflected in several geochemical proxies. The highly variable chemical index of alteration (CIA) values and the pattern in the A-CN-K plot indicate variable degrees of weathering, which in turn suggest non-steady-state weathering conditions. The high CIA values also suggest a stable tectonic setting that caused the erosion rates to decrease, which in turn caused a rise in the flux of weathered materials. The A-CN-K plot suggests sediment derivation predominantly from granodioritic and mafic rocks. Quartz grains with abraded overgrowth, abundant pseudomatrix, the presence of metasedimentary rock fragments, and variation in Zr/Sc support the presence of recycled source. The trace element compositions are consistent with a mixed source with differentiated felsic upper continental crust (UCC) as well as a more primitive mafic source. In significant contrast to most post-Archean greenstone successions, the rocks here display rare earth element patterns similar to those of the post-Archean shales. Recycling and intracrustal fractionation processes imply craton stabilization and confirm the existence of a Mesoarchean continental crust comparable to the post-Archean UCC. Here we infer a modern-day-like intracratonic setting for this succession on the basis of the geochemical fingerprints. The sandstone composition provides evidence in favor of modern-style plate tectonics during the Mesoarchean.

Retroarc foreland basins in contractional arc settings contain evidence of temporal and spatial variations in magmatic activity, deformation, and exhumation along the continental margin and serve as excellent recorders of subduction dynamics through time. The Cacheuta basin, northwestern Mendoza Province, Argentina, is situated within the transition zone between the Pampean flat-slab subduction segment north of 33°S and the normal-dipping slab segment of the Southern Volcanic Zone to the south, and it records a detailed history of Andean orogenic exhumation at this latitude. The integration of sedimentologic, stratigraphic, geochronologic, and sediment provenance data from the Cacheuta basin constrains orogenic exhumation patterns and basin evolution during basin development. Cacheuta basin strata record at least a 12 m.y. period of basin evolution (ca. 20 Ma to younger than 7.5 Ma), based on new geochronology. The timing of initial basin subsidence is constrained by the lowermost sample in the Marino Formation, which yielded a maximum depositional age of 19.2 ± 0.26 Ma, ∼4 m.y. earlier than previous interpretations. Conglomerate clast counts, thin section petrography, and detrital zircon analyses, coupled with distinct sedimentologic variations, record progressive orogenic exhumation of the Cordillera Principal, Cordillera Frontal, and Precordillera during early to middle Miocene time. Examination of basinal strata demonstrate that uplift of the Cordillera Principal, Cordillera Frontal, and Precordillera, and simultaneous development of the Cacheuta retroarc foreland basin, in the early to mid-Miocene was the result of contractional deformation and crustal thickening during normal subduction-related orogenic processes and did not result from the development of the flat slab in late Miocene time.

We have examined the Triassic sediments in the west Qinling terrane, northeastern Tibet. These sediments consist mainly of flysch and shallow-sea and fluvial deposits with abundant lithic and heavy mineral detritus, sandwiched between and overlying Late Paleozoic and Early-Middle Triassic ophiolitic mélanges. Volcanic and metamorphic detritus dominates the lithic component of Lower Triassic sandstones accompanied by high Cr-spinel, pyroxene, and magnetite contents, indicating a mixed ophiolite and metamorphic source. Detrital mineral geochemistry further suggests that ophiolitic, high-grade metamorphic, basic, and intermediate-acidic igneous rocks must have been exposed and deeply eroded in their source area. Abundances of zircon, rutile, garnet, tourmaline, and epidote are greater in the Middle Triassic samples, and granitic and volcanic sources are the major contributors of detrital clasts. Considering these new observations on sedimentary petrography and detrital heavy mineral geochemistry, along with published data on paleocurrents, detrital zircon U-Pb ages, sedimentary facies, and regional magmatism, we suggest that these Triassic sediments represent the sedimentary fill of a forearc basin that overlies a late Paleozoic ophiolitic complex. A south-facing Andean-type convergent continental margin system developed along the southern margin of the North China block during the Triassic, in response to northward subduction of the Paleotethyan Ocean.